All real numbers less than -15 in interval notation

Which expression is equivalent to (3^2)^-2 a.-81 b.-12 c.1/81 d.1/12

Acoffee shop orders at most $3,500 worth of coffee and tea. the shop needs to make a profit of at least $1,900 on the order. the possible combinations of coffee and tea for this order are given by this system of inequalities, where c = pounds of coffee and t = pounds of tea: 6c + 13t ≤ 3,500 3.50c + 4t ≥ 1,900 which graph's shaded region represents the possible combinations of coffee and tea for this order?

Sum of the interior angles of a pentagon